Introduce QueryGroups / Keyword Sets

[rladstaetter]

Currently, a user can add as many queries as he likes to a specific log file.

LogoRRR should be enhanced such that it is possible to group queries. Those groups could then be selected easily. For example, one would create a QueryGroup which contains one or more SearchTags (A search tag is a search string and an associated color) and a descriptive name.

Such QueryGroups should be persisted and it should be easy to select those QueryGroups (For example via a DropDown Selection). LogoRRR could provide a set of default QueryGroups which contain typical search strings (like 'error', 'exception', 'failure' ... ).